(a) Field of the Invention
The present invention relates to a squeeze roll for squeezing liquid from cloth being treated in a spread state.
The function of such squeeze rolls is dual; to provide uniformity in the squeeze effect and a high rate of squeeze of liquid. The invention is concerned with uniformity in the squeeze effect.
(b) Description of the Prior Art
Generally, when cloth is passed between rolls which squeeze liquid therefrom, it is desirable to press the cloth as uniformly as possible over the entire width of the cloth.
To this end, it is necessary that the pressure distribution between the rolls be maintained uniform over the entire width of the rolls.
Squeeze rolls heretofore used in general tend to deflect during the pressure loading in such a manner that their middle portions are displaced away from each other with a higher pressure exerted on the opposite ends of each roll, so that it has been impossible to attain uniformity in the squeeze effect.
In order to eliminate this drawback, there has already been proposed uniformly squeezing roll as shown in FIG. 1, which comprises a support shaft 1 and a cylindrical tube 2 fixed to said support shaft at the middle portion thereof.
In the squeeze roll shown in FIG. 1, if the length l of the middle fixing portion along which the support shaft 1 and cylindrical tube 2 are fixed together is designed to have a suitable value a, the cylindrical tube 2 will not substantially deflect during the pressure loading (refer to a line A in FIG. 2), so that a uniform pressure distribution can be attained over the entire width of a rubber cover 3.
If the length l of the fixing portion is designed to have a greater value than a, the deflection of the cylindrical tube 2 approaches the deflection line D of the support shaft 1 (refer to a line B in FIG. 2), resulting in the middle portion being pressurized less strongly than the opposite ends (i.e., the selvage-weighted state), the squeeze effect being such that the widthwise distribution of moisture content of the squeezed cloth is in the center-deepened state.
Conversely, if the length l of the fixing portion is designed to have a value smaller than a, the deflection of the cylindrical tube 2 resembles a line C in FIG. 2 which is curved opposite to the deflection line D of the support shaft 1, resulting in the central portion being pressurized more strongly than the opposite ends (i.e., the center-weighted state), the squeeze effect being such that the widthwise distribution of moisture content of the squeezed cloth is in the center-lightened state.
In this way, the deflection line of the cylindrical tube 2 varies according to the length l of the fixing portion. Under these circumstances, however, once the length l is determined and the roll produced, it is no longer possible to change the deflection line of the cylindrical tube 2 and hence the nature or pattern of the distribution of pressure on the squeeze roll.
For example, supposing 1=a, a uniform pressure distribution can be attained over the entire width of the roll irrespective of the magnitude of the pressure exerted thereon. This uniformity in pressure distribution, however, can be ensured only on condition that the cloth being passed has a width substantially equal to the roll width or that the cloth is sufficiently thin in thickness and the rubber cover 3 has sufficient elasticity. If, therefore, cloth whose width is much narrower than the roll width and which is relatively thick is passed, it does not necessarily follow that the above mentioned uniformity can be attained.
Further, in some dyeing processes, even if the uniformity is secured by the squeeze rolls in the preceding process, it frequently happens that the final finish on the cloth is not uniform widthwise thereof owing to nonuniformity in the drying or steaming treatment in the subsequent processes.
In such cases, the squeeze roll of FIG. 1 described above has the disadvantage of being incapable of optionally adjusting the distribution of the squeeze effect.